skyjedi2005 said:
The trailer had the same bad voice over guy for palpatine as force unleashed. Billionaire Lucas could not afford mcdiarmid for the game, or james earl jones for vader. They used Chad vader, and he suprisingly did a good job. As good as would be expected if it was a fanfilm and not an official lucas product. Though the Soundtrack was pretty good.

I doubt Lucas had any input, or concern, over the voice actor casting. I imagine he gave the team a budget, and rich actors like McDiarmid and Jones didn't feel like flying in to spend a day or two in the booth for something as seemingly unimportant as a video game.